For the Rub: In a medium sauté pan over medium flame, heat the olive oil until hot but not smoking. Fry the dried chillies, 1 or 2 at a time, until they puff and brown, about 10 seconds. Do not let them burn. Drain on paper towels and set aside until cool and crisp.

In a spice mill, grind the chillies in batches until they are finely powdered. Place the powder, the garlic, salt and oregano in a food processor and process until you have a saltlike spice rub. If it seems wet, spread onto a tray and let dry in a cool oven for about an hour.

Light the grill. Put the steak on a platter. Sprinkle both sides with the Chipotle Rub and onion. Moisten with beer and ½ cup of the olive oil. Marinate for up to 30 minutes, while the grill heats.

Remove the steak from the marinade, shake off any excess, but leave some onion.

Oil the BBQ grill. Cook the steak over a blazing hot fire, turning as necessary, until crusty and cooked medium-rare, about 3 minutes. Remove and rest for 3 minutes before carving.

Brush the shallots with oil. Season with salt and pepper. Reduce the heat to medium. BBQ till browned and tender, about 3-5 minutes.

To serve, slice the steak thinly across the grain. Pile on a warm platter along with tortillas and shallots.

Garnish with coriander and lime. Serve with desired salsas and guacamole.

Note: Flank and rump steak also work with this dish. Store the Chipotle Rub in a covered container indefinitely. You can use the Rub for various meats and poultry also.